AlignedAllocator#

#include <hpk/alignedAllocator.hpp>

The AlignedAllocator class is an Allocator that provides cacheline-aligned memory, which is recommended for performance reasons.

This header file also defines the free function allocateMemory(), which uses AlignedAllocator by default to provide memory managed by a std::unique_ptr.

This is a header-only implementation.

CLASS

template<class T, std::size_t align = hardware_constructive_interference_size> struct AlignedAllocator#

An allocator that provides aligned memory.

AlignedAllocator allocates memory using std::aligned_alloc and satisfies the C++ named requirements for an Allocator.

The default alignment is std::hardware_constructive_interference_size if that is defined; otherwise, 64 bytes.

Examples:

// Construct a std::vector whose data is (the default) 64B-aligned and
// initialize it with 10 floats of value 0.0f.  (Note that the type of
// v1 is not std::vector<float>, as that uses std::allocator.)
auto v1 = std::vector<float, hpk::AlignedAllocator<float>>(10);

// Construct an empty std::vector whose data will be 32B-aligned.
// (Note that the types of v1 and v2 are not the same.)
auto v2 = std::vector<float, hpk::AlignedAllocator<float, 32>>();

Public Types

using value_type = T #: T, a cv-unqualified object type

Public Functions

inline constexpr AlignedAllocator() noexcept#: Default constructor.

template<class U> inline constexpr AlignedAllocator(const AlignedAllocator<U, align>&) noexcept#: Copy constructor.

inline T *allocate(std::size_t n) const#

Allocates uninitialized storage suitable for an array object of type T.

Allocates aligned memory for n elements of type T, but does not construct array elements. If n == 0, returns nullptr. If allocation fails and exceptions are enabled, an exception is thrown. If allocation fails and exceptions are disabled (e.g., by a compiler flag), then nullptr is returned.

inline void deallocate(T *p, std::size_t) const noexcept#

Deallocates storage pointed to by p, which was a value returned by a previous call to allocate().

Note that this does not call the destructor of the object pointed to by p.

template<class L, std::size_t alignL, class R, std::size_t alignR> inline bool operator==(const AlignedAllocator<L, alignL>&, const AlignedAllocator<R, alignR>&) noexcept#: Returns true. The storage allocated by any AlignedAllocator can be deallocated through another one, regardless of template parameters.

template<class L, std::size_t alignL, class R, std::size_t alignR> inline bool operator!=(const AlignedAllocator<L, alignL>&, const AlignedAllocator<R, alignR>&) noexcept#: Returns false.

template<class U> struct rebind#

FUNCTION

template<typename T, class Allocator = AlignedAllocator<T>> auto hpk::allocateMemory(std::size_t n, Allocator &&alloc = Allocator())#

Allocates memory for n elements of type T

More specifically, the return value is a std::unique_ptr<T, hpk::Deleter<Allocator>>. If Allocator is not specified, hpk::AlignedAllocator<T> is the default. Note that T must be trivially destructible (e.g., a non-class type compatible with the C language).

Examples:

// Allocate (the default) 64B-aligned memory for 10 floats.
auto tmp1 = hpk::allocateMemory<float>(10);

// Allocate 8B-aligned memory for 20 floats.
auto tmp2 =
    hpk::allocateMemory<float, hpk::AlignedAllocator<float, 8>>(20);

// Allocate memory for 30 floats using the standard allocator.
auto tmp3 = hpk::allocateMemory<float, std::allocator<float>>(30);

// Use an instance to allocate 128B-aligned memory for 40 doubles.
auto alloc = hpk::AlignedAllocator<double, 128>();
auto tmp4 = hpk::allocateMemory<double>(40, alloc);

Returns:: std::unique_ptr that owns the allocated memory.